OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..220
EXAMPLE
15552*phi(15552)*phi(phi(15552))=373248^2.
MATHEMATICA
esQ[n_]:=Module[{e=EulerPhi[n]}, IntegerQ[Sqrt[n e EulerPhi[e]]]]; Select[Range[31000], esQ] (* Harvey P. Dale, Dec 16 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Resta, Feb 13 2006
STATUS
approved